Molecular design of a solvent-free spiropyran-containing DNA material with triple external stimuli-responsive behavior

Abstract

External stimuli-responsive behavior allows smart materials to gain controllable physicochemical changes. Compared to single stimulus response, the multiple stimuli-responsive behavior makes materials suitable for accommodating different environments, which is highly desired but appreciably more difficult to be addressed. In this study, a spiropyran-containing ammonium surfactant SPA is designed and synthesized for the electrostatic complexation with DNA, affording the ionic biomaterial DNA-SPA with a triple stimuli-responsive behavior. The treatments of UV irradiation and heating can promote fast ring-opening isomerization of DNA-SPA by giving distinct orange-to-purple color change. These properties make DNA-SPA a good candidate biomaterial for information recording and temperature indication. DNA-SPA also responds to humidity by showing linear fit between absorption intensity and relative humidity, providing the potential use as a hygrometer. The half-life of the ring-opening isomer of DNA-SPA favors the stable indications of UV irradition, temperature and humidity, and the sensitivity of ring-opening isomer to Vis light promotes the recyclable use of such biomaterial. This study provides a designing strategy for the fabrication of multiple external stimuli-responsive functional materials, opening a new pathway for gaining smart biomaterials capable of working in various fields.